Static isolator

Abstract

Static isolator for the DC supply circuit of a load (MO) in the event of a surge, consisting of a dipole intended to be inserted into the power circuit of the load and comprising means for detecting a surge (R1, R2, T3, CI), means for filtering and storing the supply voltage (C, R1), means for cutting off the supply to the load (T3, R2, R8, R9, T4, T1, R7, R4), means for detecting the disappearance of the supply voltage (C, R1, R3, R6, T6) and means for erasing the storage means (R2, R6, T3, T6).

I claim: 
     
       1. A static isolator for the DC supply circuit of a load (MO) in the event of a surge, consisting of a dipole (SS) intended to be inserted into the power circuit of the load, this dipole consisting of discrete components and comprising means for detecting a non-fleeting surge (R1, R2, T3, CI), means for filtering and storing the supply voltage (C, R1) which are intended to suppress the effect of a fleeting surge upon the energizing of the load and for retaining in memory the presence of the supply voltage and means for cutting off the supply to the load (T3, R2, R8, R9, T4, T1, R7, R4) which are controlled by the means for detecting a surge, wherein the components of the dipole furthermore constitute means for detecting the disappearance of the supply voltage (C, R1, R3, R6, T6) and means for erasing the storage means (R2, R6, T3, T6). 
     
     
       2. The static isolator as claimed in claim 1, wherein several components of the dipole (C, R1, R2, R6, T3, T6) intervene in more than one function of the dipole. 
     
     
       3. The static isolator as claimed in claim 2, wherein the means for filtering and storing the supply voltage consist essentially of a capacitor (C) and wherein the means of erasure consist of a short-circuit controlled by this capacitor (R2, R6, T3, T6). 
     
     
       4. The static isolator as claimed in claim 3, wherein the dipole is arranged between the positive terminal of the supply source and the load and wherein the dipole comprises, between its terminals, a first resistor (R3), a capacitor (C) in series with a second resistor (R1) and a Zener diode (Z) in parallel with the capacitor so as to limit the voltage at the terminals of the capacitor, an integrated circuit (CI), constituting a threshold value circuit, in series with a diode (D) and a third resistor (R6), the common point of the integrated circuit and of the diode being linked to the common point of the capacitor and of the second resistor, a first transistor (T1) in series with a fourth resistor (R7) and whose base is linked via a fifth resistor (R4) to the output (S) of the integrated circuit, a sixth and a seventh resistor (R8, R9) in series with a second transistor (T4) whose base is linked to the common point of the first transistor (T1) and of the fourth resistor (R7) and a third transistor (T3) in series with an eighth resistor (R2) and whose base is linked to the collector of the fourth transistor (T6), the emitter of this fourth transistor being linked to the common point of the capacitor (C) and of the second resistor (R1), its base being linked to the common point of the diode (D) and of the third resistor (R6), the means for detecting a surge being made up of the second (R1) and eighth (R2) resistors, of the integrated circuit (CI) and of the third transistor (T3),   the means for filtering and storing the supply voltage being made up of the capacitor (C) and of the second resistor (R1),   the means for cutting off the supply to the load being made up of the fourth, fifth, sixth, seventh and eighth resistors (R7, R4, R8, R9, R2) and of the first, second and third transistors (T1, T4, T3),   the means for detecting the disappearance of the supply voltage being made up of the first, second and third resistors (R3, R1, R6), of the capacitor (C) and of the fourth transistor (T6) and   the means for erasing the storage means being made up of the capacitor (C), of the third and fourth transistors (T3, T6) and of the third and eighth resistors (R6, R2).